The 2.5-inch XT drive is Seagate's third generation hybrid drive and features a 2-platter, 7,200rpm disk drive fitted with either a 4GB fast SLC flash cache in the 500GB product or an 8GB SLC NAND cache in the 750GB model. This larger product comes with a 6Gbit/s SATA interface while the smaller one makes do with the slower 3Gbit/s SATA link. We understand that the larger model has a 32MB buffer and a sequential read bandwidth of approximately 135MB/sec. How does the Tosh hybrid compare?

Like the curate's egg, Tosh's 2.5-inch hybrid is good in parts. According to reports it has an 8GB SLC NAND cache and the aforesaid capacity up to 1TB. It's bandwidth is just 80GB/sec, seemingly unimpressive.

We don't know the interfaces used, nor the buffer cache size, nor the spin speed, but El Reg imagines Tosh will match Seagate with a 6Gbit/s interface, SAS or SATA, we don't know which. There are Toshiba MQ01ABD and MK1059GSM 2.5-inchers spinning at 5,400rpm which have an up to 1TB capacity, and either could be the disk inside the hybrid. The company doesn't sell a 1TB, 7,200rpm 2.5-inch drive – yet.

We expect a Tosh hybrid drive for Ultrabooks to be announced by the end of the year. Western Digital is probably busy with its hybrid disk development too and keeping schtum, as it usually does. ®